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Maintaining Iowa's Secondary Road
Environment
Final Report lowa Highway Research Board
Project HR-289
March, 1989
Highway Division
lowa Department f p - 0 f Transportation
Final Report Iowa Highway Research Board
Project HR-289
Maintaining Iowa's Secondary Road Environment
Mark Callahan Secondary Road Research Coordinator
(515) 239-1382 Office of Materials
Iowa Department of Transportation Ames, Iowa
February 1989
ABSTRACT
The Iowa count ies have been successful i n main ta in ing a good
roadway environment on our 90,000 m i l e secondary road system.
However, county highway personnel must remain v i g i l a n t i n de-
t e c t i ng, d iscover ing and c o r r e c t i n g p o t e n t i a l problems i f our
roads are t o remain so.
Th is p resenta t ion was developed f o r those county personnel who
work and t r a v e l on secondary roads. The presenta t ion d i s -
cusses th ings county personnel can look f o r dur ing t h e i r d a i l y
operat ions which cou ld p o s s i b l y c rea te a p o t e n t i a l problem.
I f these s i t u a t i o n s are uncovered and cor rec ted i n a t i m e l y
manner, our secondary road system w i l l be maintained i n an
appropr ia te manner.
PAGE 2
ACKNOWLEDGEMENT
Engineering Study HR-289 was sponsored by the Iowa Highway Re-
search Board and t h e Iowa Department o f Transportat ion. Fund-
i n g f o r the p r o j e c t was from t h e Secondary Road Research Fund
i n the amount o f $12,800.
PAGE 3
1. Blank
2. Car T rave l i ng on a Secondary Road
3. Ch i ld ren Ge t t i ng on School Bus
4. Car T rave l i ng on Sec- ondary Road
5. Paving T r a i n
6. D r i v e r ' s Educat ion Car
7. S h e r i f f ' s Car
8. "Main ta in ing Iowa's Secondary Road Envi- ronment"
9. Standard Spec. Reg.
10. Guide Safety Features f o r .....
*
*Iowans who t r a v e l secondary roads
regard these roads as a very important
p a r t o f t h e i r l i v e s . *These highways
prov ide a means o f t ranspor t i ng pro-
ducts t o market and c h i l d r e n t o school.
They a r e a l s o l i n k s t o nearby c i t i e s
and towns.
*Nearly 3.8 b i l l i o n veh ic le m i l es
o f t r a v e l occur each year on Iowa's
nea r l y 90,000 m i l e secondary road sys-
tem. Accidents do happen. *However,
improvements i n highways, * i n veh ic les ,
i n d r i v e r education, i n l e g i s l a t i o n ,
*and i n enforcement have combined t o
lessen the p o t e n t i a l f o r acc idents. I f
our highways are t o cont inue t o p rov ide
a good roadway environment, these e f -
f o r t s need t o be continued.
*This p resenta t ion was developed
t o he lp county highway department per-
sonnel i n t h e i r e f f o r t t o main ta in and
improve t h e roadway environment. *The - presen ta t i on i s no t a standard, spec-
i f i c a t i o n o r regu la t i on . *Most of the
i n fo rma t ion contained i n t h i s r e p o r t
can be found i n t h e "Safety Features
f o r Local Roads and St ree ts" manual
11. Veh ic le on Mud Road
12. Modern County Road
13. 18 ft. Wide County PCC Road
prepared by the Nat ional Highway I n s t i -
t u t e o f the Federal Highway Adminis-
t r a t i o n .
* A t the t ime the federa l a i d h igh-
way system was es tab l ished i n Iowa i n
1917, the i n te rcoun ty road system had
6000 mi les , the county system had
10,000 mi les , and the township road
system had 88,000 mi les. The c u r r e n t
90,000 m i l e secondary system, f o r t h e
most p a r t , has evolved from these e a r l y
roadways. These roads were o r i g i n a l l y
developed f o r horse drawn t r a f f i c . *As
t h e type o f t r a f f i c changed, t h e stand-
ards f o r design, cons t ruc t i on and main-
tenance changed. Law changes i n t h e
19601s, which permi t ted the cou r t s t o
hear c la ims f o r damages aga ins t the
count ies and state, have made highway
admin is t ra to rs acu te l y aware o f t h e
problem o f changing roadway uses and
standards. *It would take l a r g e sums
o f money t o b r i n g a l l o f iowa's h igh-
ways up t o c u r r e n t standards. I t ap-
pears reasonable t o conclude, however,
t h a t c u r r e n t l e v e l s o f highway expendi-
t u res r e f l e c t the v iewpoint o f a
PAGE 5
m a j o r i t y o f c i t i z e n s regard ing the
va lue o f a good roadway environment.
The p u b l i c has demonstrated l i t t l e
wi 11 ingness t o suppor t s u b s t a n t i a l i n -
creases i n fund ing f o r these measures.
14. I A Laws Pe r ta in ing t o *This i s a l s o r e f l e c t e d i n recent l eg - Transpor ta t ion
i s l a t i o n which reads "A c l a i m under
t h i s chapter s h a l l n o t be a l lowed f o r
f a i l u r e t o upgrade, improve o r a1 t e r
15. Asphal t Overlay P r o j e c t
16. Road Roadside Signing Maintenance
any aspect o f an e x i s t i n g highway, sec-
ondary road, o r s t r e e t t o new, changed
o r a1 te red design standards" (Sec t ion
25A.14 o f t he Iowa Code).
*This does no t mean count ies
shou ldn ' t make any improvements t o ex-
i s t i n g roads. I t does, however, a l l o w
the count ies t o spend the a v a i l a b l e
money where i t w i l l p rov ide the maximum
b e n e f i t .
Despi te having a l i m i t e d amount of
money, t he re a re s t i l l many th ings we
can do i n day t o day opera t ions which
can he lp ma in ta in a good roadway env i -
ronment. *This p resen ta t i on w i l l cover
severa l t op i cs , each o f which has an
impact on t h a t environment.
PAGE 6
17. Tire-Road Surface Contact
18. Gravel Road
19. F e r t i l i z e r Spreader
20. T i t l e "Main ta in ing ,I . . . . . . . .
21. Gravel Road With Crown
The road, roadside, s ign ing and
maintenance are a l l f a c t o r s o f concern
t o county highway departments.
*Most d r i v e r s do n o t c o n t i n u a l l y
t h i n k about the p a r t the road sur face
p lays i n c o n t r o l o f t h e i r veh ic le .
However, t h e con tac t between a veh i -
c l e ' s t i r e s and t h e road sur face i s i m -
por tan t . Since t h i s contac t occurs a l l
the t ime, i t may be taken f o r granted
by d r i v e r s .
*Over 75% o f the county road sys-
tem i s g ranu lar sur faced roads. *Traf -
f i c and weather c o n t i n u a l l y a f f e c t
these surfaces. *The presentat ion,
"Mainta in ing Granular Surfaced Roads",
developed by the Iowa DOT f o r secondary
roads, d e t a i l s many o f the maintenance
techniques used t o keep these surfaces
i n good cond i t ion .
*The s imp les t way t o slow down t h e
development o f pot-holes, washboarding,
and rough surfaces i n general i s by
main ta in ing a proper crown t o a l l o w wa-
t e r t o d r a i n t o the d i tches .
PAGE 7
22. Water i n Potholes
23. Water i n Sec. D i t c h Along Windrow
24. Repair ing Pothole With Shovel
25. Water i n Potholes
26. Cross Sect ion Pro- f i l e s
27. Potholes i n Bituminous Surface
*Granular surfaced roads w i t h poor
crowns t r a p water, causing t h e c r u s t t o
become sa tura ted and break up. *L ike-
wise, windrows o f ma te r i a l a t t h e ou te r
edge o f the road sur face form secondary
d i t ches which i n h i b i t sur face drainage
and hasten d e t e r i o r a t i o n o f the sur -
face.
*Although n o t always p r a c t i c a l , i n
c e r t a i n s i t u a t i o n s i t may be bes t t o
s top and r e p a i r holes, r u t t e d areas and
poor sur face drainage cond i t i ons w i t h a
shovel. *Reshaping i s occasional 1 y
needed t o remove pot-holes and
washboard areas t o r e s t o r e the crown.
*Maintenance o f the supere levat ion
o f curves i s a l s o h e l p f u l i n p a r t i a l l y
o f f s e t t i n g c e n t r i f u g a l fo rces of a ve-
h i c l e rounding a curve. Superelevat ion
i s where the ou ts ide edge o f the curve
i s h igher than the i n s i d e edge.
*The hard surfaced roadway system
i s much more r e s i s t a n t t o d e t e r i o r a t i o n
caused by t r a f f i c and weather. How-
ever, when pot-holes, d ips, bumps and
rough surfaces do develop, they are
PAGE 8
more difficult to correct. When these
types of conditions are discovered, em-
ployees should inform their immediate
supervisor so remedial action can be
28. Pavement, Shoulder & taken. Ditch
*The shoulder is another part of
29. Shoulder Functions
30. Granular Shoulder
the road surface which plays a role in
the roadway environment. Problems may
occur when shoulders are not con-
structed or maintained properly.
*Shoulders serve several func-
tions. The most important one is to
stabilize the roadbed. However, shoul-
ders also may provide a refuge for
stopped vehicles, provide an "escape
route" to avoid a collision with an-
other vehicle and provide a recovery
area when a driver drifts or strays off
the road.
*It is common practice to have a
shoulder slope equal to or greater than
the slope of the road. A shoulder
should be maintained in accordance with
the applicable pol icy in order to best
serve these functions.
PAGE 9
31. Rut on H i l l
32. Edge Rut on Curve
33. Washout on Granular Surfaced Road
34. Hay on Road
35. M u f f l e r on Road
36. Logs on Shoulder
*Shoulders on steep h i l l s o r
curves deserve d i f f e r e n t a t t e n t i o n .
Heavy r a i n s may cause unacceptable edge
r u t s t o form by eroding t h e s o i l o r
rock on h i l l s . *On curves, veh i c les
occas iona l l y s t r a y on to t h e shoulder
area causing increased wear. Some
shoulder problems may r e q u i r e more than
r o u t i n e maintenance. *Inform your im-
mediate superv isor when the re i s an un-
acceptable edge r u t o r shoulder
washout. I t may need t o be marked o r
signed u n t i l maintenance can be accom-
p l ished.
*Other areas o f concern are de-
b r i s , windrows o f aggregate and loose
aggregate on pavements and paved
br idges. *Rocks o r e a r t h s l i des ,
f a l l e n branches, a r t i c l e s dropped o f f
vehic les, t rash , o r dead animals on
h igh- ways can be obstac les t o d r i ve rs .
*When these types o f t h ings a r e spot ted
o r repor ted, they should be removed.
I f l e f t on the highway they may cause
an i n a t t e n t i v e m o t o r i s t t o panic and
swerve i n t o the o the r lane. Also, when
deb r i s i s h i t i t can be thrown i n t o t h e
pa th o f o the r vehic les.
PAGE 10
37. Ma in ta iner Forming Windrow *Windrows o f aggregate are an una- i n Middle o f Road
voidable r e s u l t o f smoothing the road
38. Motor Grader P u t t i n g Windrow i n Middle of Road
39. Motor Grader P u t t i n g Windrow Along Edge o f Road
40. Wide Right-of-way
41. Narrow Right-of-way
sur face t o permi t e f f i c i e n t t r a v e l .
Windrows created du r ing reshaping w i l l
gene ra l l y be l a r g e r than storage
windrows. *Keep i n mind t h a t t r a f f i c
w i l l be us ing t h e road du r ing b lading.
T ry t o p o s i t i o n the windrow toward t h e
center so veh ic les can t r a v e l i n t h e i r
lane w i t h as l i t t l e encroachment on the
shoulder as p rac t i cab le . *Storage
windrows du r ing d r y per iods are neces-
sary t o s t o r e loose aggregate. These
windrows are u s u a l l y l e f t on t h e shoul-
der o u t o f the t r a v e l e d p o r t i o n o f t h e
road. The he igh t and s i z e o f these
windrows should be kept as smal l as i s
p r a c t i c a l so t h a t s a f e t y and drainage
are maintained.
*It i s genera l l y p re fe rab le t o
b u i l d roadways w i t h wide, f l a t areas on
each s ide t o b e t t e r serve t h e var ious
func t ions previous1 y s tated. *However,
i n r e a l i t y most l o c a l roads have l i m -
i t e d r igh ts -o f -way which make wide,
f l a t slopes impossible. Steeper
roadside slopes must be used and
d i t ches must be b u i l t c l ose r t o t h e
42. Cross Sect ion From CL Through D i t c h
*The p r i n c i p a l p a r t s o f the
roadside and d i t c h areas are shown
here. Slopes next t o shoulders should
be as f l a t as p r a c t i c a l t o b e t t e r serve
those func t ions .
Clear Zone o f a Gran- *The concept o f a c l e a r zone has u l a r Surfaced Road
evolved f o r design o f highways. The
44. I n t e r s t a t e Highway
45. Stop Ahead Sign
c l e a r zone i s the d is tance between t h e
edge o f t h e t rave led lane and the near-
e s t o b j e c t o f substance. The amount o f
c l e a r zone requ i red i s based on the
type o f roadway and t h e t r a f f i c speed.
*Obviously, t h e c l e a r zone des i red i s
l a r g e r f o r i n t e r s t a t e roads than f o r
county roads.
The o f f i c i a l wording i s
. . . . . . . . I t It i s des i rab le t o p rov ide a
roadside c l e a r o f ob jec ts o r cond i t i ons
f o r a d is tance cons i s ten t w i t h the
speed, t r a f f i c volume, and geometric
cond i t i ons o f the s i t e . " *The p r a c t i -
c a l w id th o f t h i s c l e a r zone i s v a r i - - able, p a r t i c u l a r l y f o r l o c a l roads.
PAGE 12
A c l e a r zone of 10 f e e t i s gener-
46. Railroad Overpass a l l y acceptable. *Such things as r a i l -
47. Bridge Rail/Object Marker road overpasses, culver t headwall s *and
bridge end-rails b u i l t according t o
ear l i e r standards may leave a smal l e r
c lea r zone. Obviously, upgrading these
items i s programmed based on a p r i o r i t y
system. Generally object markers a r e
used t o a l e r t motorists of these items.
Drainage s t ructures w i t h i n the
right-of-way a re a necessity, but they
may a l so represent a potential obsta-
48. Culvert Pipe Not Close t o c le . *The potential problems of drain- Roadway
age s t ruc tures i s reduced as the ends
a re placed f a r the r from the roadway.
49. Culvert With Protective *When a s t ruc ture end must be placed Cover
close t o the roadway, i t i s desi rable
t h a t i t be designed so vehicles can
cross i t safe ly or a re prevented from
reaching i t .
50. Sketch of Side Road Culvert Location
51. Eroded Foresl ope
*Culverts under a s ide road or
driveway should normally be placed a s
f a r from the through roadway as p rac t i -
cable.
*Ruts or gu l l i e s in the foreslope
caused by erosion should be f i l l e d as
quickly as practicable a f t e r they a re
discovered.
52. Pole i n R.O.W.
53. Trees i n R.O.W.
54. Mai l Box Mounted on T rac to r
55. B u i l d i n g Debr is i n R.O.W.
56. Brush Covering Sign
57. Brush Covering Sign
*Many o f t h e ob jec ts t h a t a re
found on county roads are no t under t h e
d i r e c t c o n t r o l o f the l o c a l highway
agency. *This inc ludes e x i s t i n g u t i l -
i t y poles, t rees l e f t by ROW agreements
w i t h p rope r t y owners and drainage
d i tches . *Such th ings as odd shaped o r
overs ized ma i l box posts, equipment,
hay bales and veh ic les are genera l l y
handled by the county a t to rney i f r e -
quested by the engineer. *Cor rec t ive
a c t i o n i s bes t taken i n a t i m e l y man-
ner. A l lowing one v i o l a t i o n t o e x i s t
tends t o lead t o others. When these
types o f v i o l a t i o n s are observed, you
should n o t i f y t h e engineer.
*Obstacles o f a d i f f e r e n t type a r e
weeds and brush. Weeds can obscure v i -
s i o n a t i n t e r s e c t i o n s and driveways,
cover important signs, and h ide o the r
obstac les. *Many times your view o f
t h e road i s from a motor grader o r
t r u c k cab several f e e t i n t h e a i r . The
he igh t o f t h e eyes o f a d r i v e r o f a c a r
i s considered t o be 3f f e e t above t h e
58. Brush Covering Sign
59. MUTCD Manual
60. T r a f f i c Contro l De- v ices Handbook
road. When you t r a v e l roads o f t e n and
the brush grows s low ly the re i s a tend-
ency t o overlook t h e gradual change.
*If you n o t i c e a s i g n which i s ob-
s t r u c t e d by weeds o r hanging branches,
take appropr ia te a c t i o n t o c o r r e c t t h e
s i t u a t i o n .
Signs, markings and d e l i n e a t i o n
are the basic t o o l s a v a i l a b l e f o r g i v -
i n g messages t o d r i ve rs . These mes-
sages are h e l p f u l t o i n fo rm d r i v e r s o f
t h e i r r e s p o n s i b i l i t i e s , t o warn them of
cond i t i ons and t o he lp guide them t o
t h e i r des t ina t ions .
*The Manual o f Uniform T r a f f i c Contro l Devices,
o f t e n r e f e r r e d t o as the MUTCD, se ts
gu ide l ines f o r the design, a p p l i c a t i o n
and placement o f t r a f f i c c o n t r o l de-
v ices on a l l roads. Four addenda t o
t h e MUTCD have been produced t o respond
t o the r e s u l t s o f research studies.
Each s t a t e must e i t h e r adopt the MUTCD
o r a s i m i l a r manual having U.S. DOT ap-
proval . The Sta te o f Iowa adopted t h e
MUTCD. *A companion document "The
T r a f f i c Contro l Devices Handbook" con-
t a i n s
61. Importance o f Uni- fo rmi t y
62. Types o f Signs
supplemental i n fo rma t ion which may be
h e l p f u l i n app ly ing the MUTCD t o r e a l
wor ld s i t u a t i o n s .
*The basic aim o f t h e MUTCD i s t o
e s t a b l i s h u n i f o r m i t y i n the appearance
o f and use o f t r a f f i c c o n t r o l devices.
Un i fo rm i t y i s important because it:
Enhances recogn i t i on and under-
s tanding o f t r a f f i c c o n t r o l devices;
Promotes cons i s ten t i n t e r p r e t a t i o n
by law enforcement agencies and t h e
cour ts ;
Helps the d r i v e r r e a l i z e the mes-
sage contained i n the s i g n should be
respected;
Reduces the costs o f manufactur ing
and s t o r i n g signs;
Reduces the r i s k o f l i a b i l i t y .
*Signs are d i v ided i n t o th ree ma-
j o r groups:
Regulatory signs inform d r i v e r s o f
the "Do's" and "Don'ts" t h a t apply t o
each roadway.
Warning s igns advise d r i v e r s o f
spec ia l loca t ions , maneuvers o r a c t i v -
i t i e s . They a l s o advise d r i v e r s o f up-
coming regu la to ry signs.
63. Centerline and Edge Marking
64. Object Marker
65. Night Picture of Centerline and Edge Stripes
Guide signs give information about
routes, directions, destinations,
points of interest and services.
*Marking and delineation devices
help drivers maintain their travel
path, provide warning of upcoming
changes, and assist in identifying spe-
cial situations. "Positive" deline-
ation, such as centerline marking,
indicates the path to be followed.
*Object markers are an example of
"negative" delineation indicating areas
to be avoided. *Delineation and
markings are helpful in improving a
driver's ability to drive at night be-
cause they provide guidance to drivers
when visibility is limited to normal
head1 ight range.
66. Requirements of Ef- *The MUTCD lists five basic re- fective Traffic Con- trol Devices quirements for an effective traffic
control device. The device must:
- Fulfill a need - Command attention - Convey a clear simple meaning - Command respect of road users - Give adequate time for proper re-
67. When Selecting Signs
68. Table of Placement Distances
*The rules fo r the selection and
use of signs are:
- Use standard signs
- Keep messages simple
- Place them in standard locations
where they will be expected - Use signs
only when warranted, par t icular ly regu-
la tory and warning signs.
One of several concerns when in s t a l l i ng
a sign i s i t s distance from the point
where action i s required.
Warning signs a re primarily fo r
motorists who a re unfamiliar w i t h the
road. Adequate time fo r dr iver re-
sponse needs t o be provided.
*The 1983 revision t o the MUTCD
includes t h i s table of placement di s-
tances fo r advanced placement of warn-
ing signs.
The tab le 1 i s t s suggested m i n i m u m
sign placement distances t ha t may be
used fo r three conditions:
69. Speed L i m i t Sign
PAGE 18
Cond i t ion A i s a h igh d r i v e r
judgement c o n d i t i o n which requ i res t h e
d r i v e r t o use e x t r a t ime i n making and
execut ing a dec i s ion because of a com-
p lex d r i v i n g s i t u a t i o n , such as chang-
i n g lanes, merging o r passing.
Cond i t ion B i s a c o n d i t i o n i n
which t h e d r i v e r w i l l l i k e l y be r e -
qu i red t o stop.
Cond i t ion C i s a c o n d i t i o n i n
which t h e d r i v e r w i l l l i k e l y be r e -
qu i red t o decelerate t o a s p e c i f i c
speed.
The values contained i n the t a b l e
are f o r guidance purposes and should be
appl i e d w i t h engineer ing judgement.
The suggested minimum s i g n placement
d is tances g iven i n t h i s t a b l e may n o t
apply t o the placement o f temporary
warning signs used a t highway con-
s t r u c t i o n and maintenance s i t e s . Con-
s u l t the engineer whenever a quest ion
a r i s e s concerning the proper placement
o f warning signs.
*Regulatory signs are normal ly
placed where a requ i red a c t i o n o r pro-
h i b i t i o n begins, and then a t r e g u l a r
i n t e r v a l s t o remind m o t o r i s t s t h e regu-
l a t i o n s s t i l l apply.
The l e g a l i t y o f regu la t i ons has
70. Guide Sign
71. Route Marker
72. Sign on Secondary Road
been questioned i n the cou r t s when the
s i g n placement and the beginning of t h e
r e s t r i c t i o n do n o t co inc ide.
*Guide Signs are h e l p f u l when
placed i n advance o f , and a t , dec i s ion
po in t s where d r i v e r s must decide
whether t o cont inue s t r a i g h t o r make a
tu rn . *Confirmation rou te markers j u s t
a f t e r t h e dec i s ion p o i n t a re a l s o very
h e l p f u l t o mo to r i s t s who are u n f a m i l i a r
w i t h t h e area.
The d is tance between a s i g n and
the roadway i s very o f t e n a compromise
between the nearness des i red f o r easy
readabi 1 i t y and the separat ion from the
edge o f the pavement des i red f o r
sa fe ty .
*To prov ide some room f o r d r i v e r s
t o recover veh ic les which are ou t of
con t ro l , i t i s des i rab le t h a t signs
should no t be placed c l o s e r than s i x
fee t from the edge o f t h e shoulder on
r u r a l roads. Where t h e shoulder i s
l ess than s i x fee t , a spacing o f 12
f e e t from the edge o f the t r a v e l e d way
i s desi rable. The t r a v e l e d way i s con-
s idered t o be 20 f e e t wide f o r g ranu lar
surfaced roads.
73. Sign on Secondary Road
74. Hidden Sign
75. Vandalized Stop Sign
*The bottom of a s i g n i n a r u r a l
d i s t r i c t should be n o t l ess than 5 f e e t
above t h e plane o f t h e road. When a
supplemental p l a t e i s used on a warning
s i g n i n a r u r a l area, t h e minimum
he igh t t o t h e bottom o f the supple-
mental s i g n may be reduced t o 4 f e e t .
Signs mounted on temporary sup-
p o r t s i n maintenance areas may be
mounted a t lower heights. However, i n
a l l cases, t h e bottom o f the s i g n
should be a t l e a s t 1 f o o t above the
roadway, and should n o t r e s t on t h e
ground.
*Motor is ts may miss the messages
o f s igns they cannot see p l a i n l y . The
view o f a s i g n may be blocked because
o f i n i t i a l i n s t a l l a t i o n e r r o r , growth
o f vegeta t ion o r cons t ruc t i on a c t i v -
i t i e s . Visual blockages should be co r -
rec ted as soon as possib le. *Also,
vandal ized signs should be replaced i f
i t i s determined the s i g n can no longer
be i n t e r p r e t e d p l a i n l y by mo to r i s t s .
76. M u l t i p l e Signs
77. Old Sign S t i l l i n Place A f t e r Cor- r e c t i o n
78. Handful o f Glass Beads
*Where m u l t i p l e signs are used,
t h e most important in fo rmat ion should
be g iven p r i o r i t y . Regulatory and
warning signs should be placed i n t h e
optimum pos i t i on . They should n o t be
blocked o r obscured by o the r s igns.
Guide s igns should be re loca ted t o
o the r pos i t i ons .
*Sometimes signs remain i n p lace
a f t e r t h e cond i t ions which warranted
t h e i r i n s t a l l a t i o n have changed. They
may be unnecessary. I f so, they should
be removed o r re loca ted t o reduce s i g n
c l u t t e r and g i ve more emphasis t o t h e
remaining signs.
Pavement markings should a l s o be
mainta ined i n o rder f o r them t o be e f -
f e c t i v e . *An essen t i a l i n g r e d i e n t i n
good pavement marking i s the g lass
beads which make these markings more
v i s i b l e a t n igh t .
PAGE 22
79. Night Shot of Paint Reflectivity
80. Poor Paint Reflectivity
81. Chevrons Along a Curve
82. Delineator
*The glass beads reflect light
from a vehicle's headlights back to the
eyes of the driver. Unfortunately, the
glass beads which provide nighttime
reflectance are often gone long before
the paint is worn away. *Thus, lines
which are visible during the day may
appear "dead" at night. One method of
determining the effectiveness of line
reflectivity is to drive the road at
night. A line which reflects light
poorly would indicate that maintenance
should be done on it.
A problem with standard pavement
markings, in some situations, is that
they cannot be seen far enough in ad-
vance. *At horizontal curves located
beyond the crest of a hill, post
mounted delineators or chevrons may
provide a better indication of the path
ahead.
*Post-mounted delineators consist
of disks or panels mounted on posts.
The disks should be at least 3 inches
in diameter with a surface that will
direct light back to the driver. A
delineator may be mounted on a plastic
post which resists damage caused by im-
pacts.
83. Chevron D e t a i l *The chevron al ignment s i g n cons is ts of a
b lack chevron symbol on a y e l l o w rectangle.
Several o f these are placed i n a se r ies t o
mark the roadway path a t sharp curves. Spac-
i n g o f the signs should be such t h a t the mo-
t o r i s t s always have two i n view, u n t i l t h e
change i n al ignment e l im ina tes the need f o r
the signs.
Object markers are used t o i d e n t i f y ob-
s t r u c t i o n s w i t h i n o r nex t t o t h e roadway. The
t h r e e types o f o b j e c t markers are shown here.
84. Type 1 Object Marker x
85. Type 2 Object Marker *
86. Type 3 Object Marker *
87. Type 3 Object Markers *Obstacles w i t h i n the roadway should a t a Br idge
normal ly be i d e n t i f i e d w i t h type 1 o r type 3
markers. The downward slope o f the s t r i p e on
t h e type 3 marker i n d i c a t e s the s ide o f t h e
panel on which d r i v e r s should pass. Be sure
these s igns ge t p laced c o r r e c t l y a t obstacles.
88. Type 2 Marker a t Br idge
*Type 2 o r type 3 markers a r e used f o r
ob jec ts c lose t o t h e t r a v e l l e d way, such as
br idge abutments.
While you may n o t want t o p lace
de l i nea to rs everywhere, they a r e very e f f e c -
t i v e a t curves and a t obstacles.
89. Sign With Poor R e t r o r e f l e c t i v i t y
90. County Secretary Log- g ing a C a l l From t h e Pub l i c
91. County Personnel I n - spec t ing Sign
92. Road Maintenance Work
*Per iodic inspect ions should be made
du r ing the day t o check f o r t h e presence
o f t h e s i g n and a t n i g h t t o check f o r
q u a l i t y o f s i g n r e f l e c t i v i t y . Signs,
markings and d e l i n e a t i o n devices do n o t
l a s t f o reve r and must be expected t o wear
ou t and be replaced.
One o r two people a r e genera l l y
made respons ib le f o r s i g n maintenance.
*With 700 t o 1000 m i les o f roadway, one
o f the bes t ways t o e f f e c t i v e l y main-
t a i n t h e signs i s t o encourage p u b l i c
c a l l s , i n c l u d i n g from law enforcement,
on defects. *Also, department employ-
ees, i n the course o f t h e i r employment,
should make notes o f miss ing o r damaged
signs they n o t i c e and r e p o r t such prob-
lems t o the County Engineer o r the per -
son i n charge o f making r e p a i r s as soon
as p rac t i cab le .
*A good roadway environment can be
kept w i t h proper cons t ruc t i on and rou-
t i n e maintenance o f the road and r i g h t -
o f -way. However, maintenance work
o f t e n in t roduces a necessary problem on
93. "Road Construct ion Ahead'' Sign
94. C lear ing Drainage D i t c h
95. County Worker Spray- i n g Herb ic ide
t h e roadway. To be sure a good roadway
environment i s maintained du r ing t h i s
t ime, the county 's es tab l ished standard
ope ra t i ng procedures must be f o l l owed
as c l o s e l y as prac t icab le . *Also,
s i g n i n g must conform t o t h e MUTCD i n
t h e use o f warning signs, unless good
engineer ing judgment i nd i ca tes o ther -
wise.
Dur ing cons t ruc t i on o f a p r o j e c t
a l l work should be conf ined t o t h e con-
s t r u c t i o n l i m i t s o r r ight-of -way.
Good judgement i s needed i n de te r -
min ing where t o a l l ow the con t rac to r t o
keep h i s equipment du r ing t h e n igh t .
Keep t h e m o t o r i s t i n mind when making
t h i s decis ion.
*When performing maintenance work
on t h e r ight-of -way, care i s needed n o t
t o damage adjacent p roper t ies . *When
spraying herb ic ides on grasses and
weeds, avo id spraying farmers ' crops o r
vegeta t ion on p r i v a t e proper ty . Also,
when tr imming t rees, avo id damaging
p r i v a t e proper ty w i t h f a l l i n g branches.
96. Motor Grader Operator *Equipment operators must be aware Smoothing Shoulder
o f passing t r a f f i c w h i l e ope ra t i ng
t h e i r veh ic les on o r near t h e roadway.
PAGE 26
97. Snowplow Operating in Storm
98. County Personnel Marking Shoulder Washout
99. Cars Traveling on County Highway
*Defensive driving is the best way to
keep vehicle accidents to a minimum.
By driving carefully, abiding by the
posted speed limits and reducing speed
in adverse conditions, accidents can be
avoided. Do not hesitate to use your
head1 ights to improve your visibility.
Also, it is good practice to always use
your vehicle's warning lights when
working on or near the roadway.
*County personnel, in the course
of their employment, can play an impor-
tant role in detecting potential prob-
lems that may occur from time to time
on the secondary road system. While
driving in your county, note such
things as erosion of the shoulder,
shoulder dropoffs, potholes, ponding
water, and rough surfaces which may be
subject to maintenance under your poli-
cies. Report these to your immediate
supervisor so that timely corrections
can be made.
*Iowa's transportation agencies
have been successful in designing, con-
structing, and maintaining roadways
100. C r e d i t S l i d e
101. Acknowledgement
102. Acknowledgement
which prov ide a good roadway envi ron-
ment. Occasional ly, however, s i t u -
a t i o n s w i l l a r i s e which c rea te
p o t e n t i a l problems. I t i s our du ty t o
a c t i n a t i m e l y and proper manner t o
c o r r e c t these s i t u a t i o n s .
Iowa Highway Research Board
P ro jec t HR-289
Iowa Department o f Transpor ta t ion
Highway D i v i s i o n
For t h e i r c o n t r i b u t i o n t o t h i s presen-
t a t i o n , we would l i k e t o thank t h e f o l -
lowing:
Boone County Maintenance Staf f
S tory County Engineering S t a f f
S tory County S h e r i f f ' s Staff
Ames School D i s t r i c t
Special thanks t o M r . R. L. Carstens
f o r h i s exper t consu l ta t i on i n develop-
i n g t h i s presentat ion.
103. Blank
